If I have a model, such as a robot, I am able to swap its limb meshes out and replace them with other robot limb meshes by merely removing the limb mesh from the skeleton and attaching the new one to the appropriate bone.

Now I want to essentially do the same thing but with a skinned mesh, say a human/monster character. For example I want to swap a normal human arm for some bad-ass demon arm. How do I go about doing this as I believe I need to take into account skin/bone weights etc.